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  • gcc optimization? bug? and its practial implication to project

    - by kumar_m_kiran
    Hi All, My questions are divided into three parts Question 1 Consider the below code, #include <iostream> using namespace std; int main( int argc, char *argv[]) { const int v = 50; int i = 0X7FFFFFFF; cout<<(i + v)<<endl; if ( i + v < i ) { cout<<"Number is negative"<<endl; } else { cout<<"Number is positive"<<endl; } return 0; } No specific compiler optimisation options are used or the O's flag is used. It is basic compilation command g++ -o test main.cpp is used to form the executable. The seemingly very simple code, has odd behaviour in SUSE 64 bit OS, gcc version 4.1.2. The expected output is "Number is negative", instead only in SUSE 64 bit OS, the output would be "Number is positive". After some amount of analysis and doing a 'disass' of the code, I find that the compiler optimises in the below format - Since i is same on both sides of comparison, it cannot be changed in the same expression, remove 'i' from the equation. Now, the comparison leads to if ( v < 0 ), where v is a constant positive, So during compilation itself, the else part cout function address is added to the register. No cmp/jmp instructions can be found. I see that the behaviour is only in gcc 4.1.2 SUSE 10. When tried in AIX 5.1/5.3 and HP IA64, the result is as expected. Is the above optimisation valid? Or, is using the overflow mechanism for int not a valid use case? Question 2 Now when I change the conditional statement from if (i + v < i) to if ( (i + v) < i ) even then, the behaviour is same, this atleast I would personally disagree, since additional braces are provided, I expect the compiler to create a temporary built-in type variable and them compare, thus nullify the optimisation. Question 3 Suppose I have a huge code base, an I migrate my compiler version, such bug/optimisation can cause havoc in my system behaviour. Ofcourse from business perspective, it is very ineffective to test all lines of code again just because of compiler upgradation. I think for all practical purpose, these kinds of error are very difficult to catch (during upgradation) and invariably will be leaked to production site. Can anyone suggest any possible way to ensure to ensure that these kind of bug/optimization does not have any impact on my existing system/code base? PS : When the const for v is removed from the code, then optimization is not done by the compiler. I believe, it is perfectly fine to use overflow mechanism to find if the variable is from MAX - 50 value (in my case).

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  • Making Global Struct in C++ Program

    - by mosg
    Hello world! I am trying to make global structure, which will be seen from any part of the source code. I need it for my big Qt project, where some global variables needed. Here it is: 3 files (global.h, dialog.h & main.cpp). For compilation I use Visual Studio (Visual C++). global.h #ifndef GLOBAL_H_ #define GLOBAL_H_ typedef struct TNumber { int g_nNumber; } TNum; TNum Num; #endif dialog.h #ifndef DIALOG_H_ #define DIALOG_H_ #include <iostream> #include "global.h" using namespace std; class ClassB { public: ClassB() {}; void showNumber() { Num.g_nNumber = 82; cout << "[ClassB][Change Number]: " << Num.g_nNumber << endl; } }; #endif and main.cpp #include <iostream> #include "global.h" #include "dialog.h" using namespace std; class ClassA { public: ClassA() { cout << "Hello from class A!\n"; }; void showNumber() { cout << "[ClassA]: " << Num.g_nNumber << endl; } }; int main(int argc, char **argv) { ClassA ca; ClassB cb; ca.showNumber(); cb.showNumber(); ca.showNumber(); cout << "Exit.\n"; return 0; } When I`m trying to build this little application, compilation works fine, but the linker gives me back an error: 1>dialog.obj : error LNK2005: "struct TNumber Num" (?Num@@3UTNumber@@A) already defined in main.obj Is there exists any solution? Thanks.

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  • vector related memory allocation question

    - by memC
    hi all, I am encountering the following bug. I have a class Foo . Instances of this class are stored in a std::vector vec of class B. in class Foo, I am creating an instance of class A by allocating memory using new and deleting that object in ~Foo(). the code compiles, but I get a crash at the runtime. If I disable delete my_a from desstructor of class Foo. The code runs fine (but there is going to be a memory leak). Could someone please explain what is going wrong here and suggest a fix? thank you! class A{ public: A(int val); ~A(){}; int val_a; }; A::A(int val){ val_a = val; }; class Foo { public: Foo(); ~Foo(); void createA(); A* my_a; }; Foo::Foo(){ createA(); }; void Foo::createA(){ my_a = new A(20); }; Foo::~Foo(){ delete my_a; }; class B { public: vector<Foo> vec; void createFoo(); B(){}; ~B(){}; }; void B::createFoo(){ vec.push_back(Foo()); }; int main(){ B b; int i =0; for (i = 0; i < 5; i ++){ std::cout<<"\n creating Foo"; b.createFoo(); std::cout<<"\n Foo created"; } std::cout<<"\nDone with Foo creation"; std::cout << "\nPress RETURN to continue..."; std::cin.get(); return 0; }

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  • I want to trace logs using a Macro multi parameter always null. problem c++ windows

    - by sxingfeng
    I am using the following way to cout a function's time: #define TIME_COST(message, ...)\ char szMessageBuffer[2048] = {0};\ va_list ArgList;\ va_start(ArgList, message);\ vsprintf_s(szMessageBuffer, 2048, message, ArgList);\ va_end(ArgList); \ string strMessage(szMessageBuffer);\ CQLogTimer t(strMessage); // CQLogTimer is a self destructor,which will cout life time of its own and print szMessageBuffer. However when I use the macro this : void fun { TIME_COST("hello->%s", filePath); XXXXXX } The message generated always is hello-(null) Can Any one help? Many thanks!

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  • async_write/async_read problems while trying to implement question-answer logic

    - by Max
    Good day. I'm trying to implement a question - answer logic using boost::asio. On the Client I have: void Send_Message() { .... boost::asio::async_write(server_socket, boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Client::Handle_Write_Message, this, boost::asio::placeholders::error)); .... } void Handle_Write_Message(const boost::system::error_code& error) { .... std::cout << "Message was sent.\n"; .... boost::asio::async_read(server_socket_,boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Client::Handle_Read_Message, this, boost::asio::placeholders::error)); .... } void Handle_Read_Message(const boost::system::error_code& error) { .... std::cout << "I have a new message.\n"; .... } And on the Server i have the "same - logic" code: void Read_Message() { .... boost::asio::async_read(client_socket, boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Server::Handle_Read_Message, this, boost::asio::placeholders::error)); .... } void Handle_Read_Message(const boost::system::error_code& error) { .... std::cout << "I have a new message.\n"; .... boost::asio::async_write(client_socket_,boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Server::Handle_Write_Message, this, boost::asio::placeholders::error)); .... } void Handle_Write_Message(const boost::system::error_code& error) { .... std::cout << "Message was sent back.\n"; .... } Message it's just a structure. And the output on the Client is: Message was sent. Output on the Server is: I have a new message. And that's all. After this both programs are still working but nothing happens. I tried to implement code like: if (!error) { .... } else { // close sockets and etc. } But there are no errors in reading or writing. Both programs are just running normally, but doesn't interact with each other. This code is quite obvious but i can't understand why it's not working. Thanks in advance for any advice.

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  • Copy constructor bug

    - by user168715
    I'm writing a simple nD-vector class, but am encountering a strange bug. I've stripped out the class to the bare minimum that still reproduces the bug: #include <iostream> using namespace std; template<unsigned int size> class nvector { public: nvector() {data_ = new double[size];} ~nvector() {delete[] data_;} template<unsigned int size2> nvector(const nvector<size2> &other) { data_ = new double[size]; int i=0; for(; i<size && i < size2; i++) data_[i] = other[i]; for(; i<size; i++) data_[i] = 0; } double &operator[](int i) {return data_[i];} const double&operator[](int i) const {return data_[i];} private: const nvector<size> &operator=(const nvector<size> &other); //Intentionally unimplemented for now double *data_; }; int main() { nvector<2> vector2d; vector2d[0] = 1; vector2d[1] = 2; nvector<3> vector3d(vector2d); for(int i=0; i<3; i++) cout << vector3d[i] << " "; cout << endl; //Prints 1 2 0 nvector<3> other3d(vector3d); for(int i=0; i<3; i++) cout << other3d[i] << " "; cout << endl; //Prints 1 2 0 } //Segfault??? On the surface this seems to work fine, and both tests print out the correct values. However, at the end of main the program crashes with a segfault, which I've traced to nvector's destructor. At first I thought the (incorrect) default assignment operator was somehow being called, which is why I added the (currently) unimplemented explicit assignment operator to rule this possibility out. So my copy constructor must be buggy, but I'm having one of those days where I'm staring at extremely simple code and just can't see it. Do you guys have any ideas?

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  • errorerror C2059: syntax error : ']', i cant figure out why this coming up in c++

    - by user320950
    void display_totals(); int exam1[100][3];// array that can hold 100 numbers for 1st column int exam2[100][3];// array that can hold 100 numbers for 2nd column int exam3[100][3];// array that can hold 100 numbers for 3rd column int main() { int go,go2,go3; go=read_file_in_array; go2= calculate_total(exam1[],exam2[],exam3[]); go3=display_totals; cout << go,go2,go3; return 0; } void display_totals() { int grade_total; grade_total=calculate_total(exam1[],exam2[],exam3[]); } int calculate_total(int exam1[],int exam2[],int exam3[]) { int calc_tot,above90=0, above80=0, above70=0, above60=0,i,j; calc_tot=read_file_in_array(exam[100][3]); exam1[][]=exam[100][3]; exam2[][]=exam[100][3]; exam3[][]=exam[100][3]; for(i=0;i<100;i++); { if(exam1[i] <=90 && exam1[i] >=100) { above90++; cout << above90; } } return exam1[i],exam2[i],exam3[i]; } int read_file_in_array(int exam[100][3]) { ifstream infile; int num, i=0,j=0; infile.open("grades.txt");// file containing numbers in 3 columns if(infile.fail()) // checks to see if file opended { cout << "error" << endl; } while(!infile.eof()) // reads file to end of line { for(i=0;i<100;i++); // array numbers less than 100 { for(j=0;j<3;j++); // while reading get 1st array or element infile >> exam[i][j]; cout << exam[i][j] << endl; } } infile.close(); return exam[i][j]; }

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  • error unidentfied identfier "exams" and i dont know why in c++

    - by user320950
    // basic file operations #include <iostream> #include <fstream> using namespace std; void read_file_in_array(int exam[100][3]); double calculate_total(int exam1[], int exam2[], int exam3[]); // function that calcualates grades to see how many 90,80,70,60 //void display_totals(); int main() { int go,go2,go3; go=read_file_in_array(exam); go2=calculate_total(exam1,exam2,exam3); //go3=display_totals(); cout << go,go2,go3; return 0; }/* int display_totals() { int grade_total; grade_total=calculate_total(exam1,exam2,exam3); return 0; } */ double calculate_total(int exam1[],int exam2[],int exam3[]) { int calc_tot,above90=0, above80=0, above70=0, above60=0,i,j; calc_tot=read_file_in_array(exam); for(i=0;i<100;i++) { exam1[i]=exam[100][0]; exam2[i]=exam[100][1]; exam3[i]=exam[100][2]; if(exam1[i] <=90 && exam1[i] >=100) { above90++; cout << above90; } } return exam3[i]; } void read_file_in_array(double exam[100][3]) { ifstream infile; int num, i=0,j=0; infile.open("grades.txt");// file containing numbers in 3 columns if(infile.fail()) // checks to see if file opended { cout << "error" << endl; } while(!infile.eof()) // reads file to end of line { for(i=0;i<100;i++) // array numbers less than 100 { for(j=0;j<3;j++) // while reading get 1st array or element infile >> exam[i][j]; infile >> exam[i][j]; infile >> exam[i][j]; cout << exam[i][j] << endl; } exam[i][j]=exam1[i]; exam[i][j]=exam2[i]; exam[i][j]=exam3[i]; } infile.close(); }

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  • reverse a linked list?

    - by sil3nt
    Hi there, Im trying to reverse the order of the following linked list, I've done so, But the reversed list does not seem to print out. Where have I gone wrong? //reverse the linked list #include <iostream> using namespace std; struct node{ int number; node *next; }; node *A; void addNode(node *&listpointer, int num){ node *temp; temp = new node; temp->number = num; temp->next = listpointer; listpointer = temp; } void reverseNode(node *&listpointer){ node *temp,*current; current = listpointer; temp = new node; while (true){ if (current == NULL){ temp = NULL; break; } temp->number = current->number; current = current->next; temp = temp->next; } listpointer = temp; } int main(){ A = NULL; addNode(A,1); addNode(A,2); addNode(A,3); while (true){ if (A == NULL){break;} cout<< A->number << endl; A = A->next; } cout<< "****" << endl; reverseNode(A); while (true){ if (A == NULL){break;} cout<< A->number << endl; A = A->next; } cout<< "****"<< endl; return 0; }

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  • Convert string from getline into a number

    - by haskellguy
    I am trying to create a 2D array with vectors. I have a file that has for each line a set of numbers. So what I did I implemented a split function that every time I have a new number (separated by \t) it splits that and add it to the vector vector<double> &split(const string &s, char delim, vector<double> &elems) { stringstream ss(s); string item; while (getline(ss, item, delim)) { cout << item << endl; double number = atof(item.c_str()); cout << number; elems.push_back(number); } return elems; } vector<double> split(const string &s, char delim) { vector<double> elems; split(s, delim, elems); return elems; } After that I simply iterate through it. int main() { ifstream file("./data/file.txt"); string row; vector< vector<double> > matrix; int line_count = -1; while (getline(file, row)) { line_count++; if (line_count <= 4) continue; vector<double> cols = split(row, '\t'); matrix.push_back(cols); } ... } Now my issues is in this bit here: while (getline(ss, item, delim)) { cout << item << endl; double number = atof(item.c_str()); cout << number; Where item.c_str() is converted to a 0. Shouldn't that be still a string having the same value as item? It works on a separate example if I do straight from string to c_string, but when I use this getline I end up in this error situation, hints?

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  • When I overload the assignment operator for my simple class array, I get the wrong answer I espect

    - by user299648
    //output is "01234 00000" but the output should be or what I want it to be is // "01234 01234" because of the assignment overloaded operator #include <iostream> using namespace std; class IntArray { public: IntArray() : size(10), used(0) { a= new int[10]; } IntArray(int s) : size(s), used(0) { a= new int[s]; } int& operator[]( int index ); IntArray& operator =( const IntArray& rightside ); ~IntArray() { delete [] a; } private: int *a; int size; int used;//for array position }; int main() { IntArray copy; if( 2>1) { IntArray arr(5); for( int k=0; k<5; k++) arr[k]=k; copy = arr; for( int j=0; j<5; j++) cout<<arr[j]; } cout<<" "; for( int j=0; j<5; j++) cout<<copy[j]; return 0; } int& IntArray::operator[]( int index ) { if( index >= size ) cout<<"ilegal index in IntArray"<<endl; return a[index]; } IntArray& IntArray::operator =( const IntArray& rightside ) { if( size != rightside.size )//also checks if on both side same object { delete [] a; a= new int[rightside.size]; } size=rightside.size; used=rightside.used; for( int i = 0; i < used; i++ ) a[i]=rightside.a[i]; return *this; }

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  • C++ problem with string stream istringstream

    - by user69514
    I am reading a file in the following format 1001 16000 300 12.50 2002 24000 360 10.50 3003 30000 300 9.50 where the items are: loan id, principal, months, interest rate. I'm not sure what it is that I am doing wrong with my input string stream, but I am not reading the values correctly because only the loan id is read correctly. Everything else is zero. Sorry this is a homework, but I just wanted to know if you could help me identify my error. if( inputstream.is_open() ){ /** print the results **/ cout << fixed << showpoint << setprecision(2); cout << "ID " << "\tPrincipal" << "\tDuration" << "\tInterest" << "\tPayment" <<"\tTotal Payment" << endl; cout << "---------------------------------------------------------------------------------------------" << endl; /** assign line read while we haven't reached end of file **/ string line; istringstream instream; while( inputstream >> line ){ instream.clear(); instream.str(line); /** assing values **/ instream >> loanid >> principal >> duration >> interest; /** compute monthly payment **/ double ratem = interest / 1200.0; double expm = (1.0 + ratem); payment = (ratem * pow(expm, duration) * principal) / (pow(expm, duration) - 1.0); /** computer total payment **/ totalPayment = payment * duration; /** print out calculations **/ cout << loanid << "\t$" << principal <<"\t" << duration << "mo" << "\t" << interest << "\t$" << payment << "\t$" << totalPayment << endl; } }

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  • A program where user enters a string and the program counts the instances of the letters

    - by user1865183
    This is the first C++ program I have ever written and I'm having trouble understanding the order in which operands must be put in. This is for a class, but it looks like I'm not supposed to use the homework tag. Sorry if I'm doing this wrong. This is my input // Get DNA string string st; cout << "Enter the DNA sequence to be analysed: "; cin >> st; This seems to work ok, but I thought I would include it incase this is what I'm doing wrong. This is what I have so far to check that the input is exclusively C,T,A, or G. It runs through the program and simply prints "Please enter a valid sequnce1, please enter a valid sequence2, ... ect. I'm sure I'm doing something very stupid, I just can't figure it out. // Check that the sequence is all C, T, A, G while (i <= st.size()){ if (st[i] != 'c' && st[i] != 'C' && st[i] != 'g' && st[i] != 'G' && st[i] != 't' && st[i] != 'T' && st[i] != 'a' && st[i] != 'A'); cout << "Please enter a valid sequence" << i++; else if (st[i] == c,C,G,t,T,a,A) i++; The second half of my program is to count the number of Cs and Gs in the sequence for (i < st.size() ; i++ ;); for (loop <= st.size() ; loop++;) if (st[loop] == 'c') { count_c++; } else if (st[loop] == C) { count_c++; } else if (st[loop] == g) { count_g++; } else if (st[loop] == G); { count_g++; } cout << "Number of instances of C = " << count_c; cout << "Number of instances of G = " << count_g; It seems like it's not looping, it will count 1 of one of the letters. How do I make it loop? I can't seem to put in endl; anywhere without getting an error back, although I know I'll need it somewhere. Any help or tips to point me in the right direction would be greatly appreciated - I've been working on this code for two days (this is embarrassing to admit).

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  • I am getting the below mentioned error in my program. what will be the solution?

    - by suvirai
    // Finaldesktop.cpp : Defines the entry point for the console application. // include include include include include using namespace std; int SearchDirectory(vector &refvecFiles, const string &refcstrRootDirectory, const string &refcstrExtension, bool bSearchSubdirectories = true) { string strFilePath; // Filepath string strPattern; // Pattern string strExtension; // Extension HANDLE hFile; // Handle to file WIN32_FIND_DATA FileInformation; // File information strPattern = refcstrRootDirectory + "\."; hFile = FindFirstFile(strPattern.c_str(), &FileInformation); if(hFile != INVALID_HANDLE_VALUE) { do { if(FileInformation.cFileName[0] != '.') { strFilePath.erase(); strFilePath = refcstrRootDirectory + "\" + FileInformation.cFileName; if(FileInformation.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) { if(bSearchSubdirectories) { // Search subdirectory int iRC = SearchDirectory(refvecFiles, strFilePath, refcstrExtension, bSearchSubdirectories); if(iRC) return iRC; } } else { // Check extension strExtension = FileInformation.cFileName; strExtension = strExtension.substr(strExtension.rfind(".") + 1); if(strExtension == refcstrExtension) { // Save filename refvecFiles.push_back(strFilePath); } } } } while(FindNextFile(hFile, &FileInformation) == TRUE); // Close handle FindClose(hFile); DWORD dwError = GetLastError(); if(dwError != ERROR_NO_MORE_FILES) return dwError; } return 0; } int main() { int iRC = 0; vector vecAviFiles; vector vecTxtFiles; // Search 'c:' for '.avi' files including subdirectories iRC = SearchDirectory(vecAviFiles, "c:", "avi"); if(iRC) { cout << "Error " << iRC << endl; return -1; } // Print results for(vector::iterator iterAvi = vecAviFiles.begin(); iterAvi != vecAviFiles.end(); ++iterAvi) cout << *iterAvi << endl; // Search 'c:\textfiles' for '.txt' files excluding subdirectories iRC = SearchDirectory(vecTxtFiles, "c:\textfiles", "txt", false); if(iRC) { cout << "Error " << iRC << endl; return -1; } // Print results for(vector::iterator iterTxt = vecTxtFiles.begin(); iterTxt != vecTxtFiles.end(); ++iterTxt) cout << *iterTxt << endl; // Wait for keystroke _getch(); return 0; }

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  • template; Point<2, double>; Point<3, double>

    - by Oops
    Hi, I want to create my own Point struct it is only for purposes of learning C++. I have the following code: template <int dims, typename T> struct Point { T X[dims]; Point(){} Point( T X0, T X1 ) { X[0] = X0; X[1] = X1; } Point( T X0, T X1, T X2 ) { X[0] = X0; X[1] = X1; X[2] = X2; } Point<dims, int> toint() { //how to distinguish between 2D and 3D ??? Point<dims, int> ret = Point<dims, int>( (int)X[0], (int)X[1]); return ret; } std::string str(){ //how to distinguish between 2D and 3D ??? std::stringstream s; s << "{ X0: " << X[0] << " | X1: " << X[1] << " }"; return s.str(); } }; int main(void) { Point<2, double> p2d = Point<2, double>( 12.3, 45.6 ); Point<3, double> p3d = Point<3, double>( 12.3, 45.6, 78.9 ); Point<2, int> p2i = p2d.toint(); //OK Point<3, int> p3i = p3d.toint(); //m??? std::cout << p2d.str() << std::endl; //OK std::cout << p3d.str() << std::endl; //m??? std::cout << p2i.str() << std::endl; //m??? std::cout << p3i.str() << std::endl; //m??? char c; std::cin >> c; return 0; } of couse until now the output is not what I want. my questions is: how to take care of the dimensions of the Point (2D or 3D) in member functions of the Point? many thanks in advance Oops

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  • error C2059: syntax error : ']', i cant figure out why this coming up in c++

    - by user320950
    void display_totals(); int exam1[100][3];// array that can hold 100 numbers for 1st column int exam2[100][3];// array that can hold 100 numbers for 2nd column int exam3[100][3];// array that can hold 100 numbers for 3rd column int main() { int go,go2,go3; go=read_file_in_array; go2= calculate_total(exam1[],exam2[],exam3[]); go3=display_totals; cout << go,go2,go3; return 0; } void display_totals() { int grade_total; grade_total=calculate_total(exam1[],exam2[],exam3[]); } int calculate_total(int exam1[],int exam2[],int exam3[]) { int calc_tot,above90=0, above80=0, above70=0, above60=0,i,j; calc_tot=read_file_in_array(exam[100][3]); exam1[][]=exam[100][3]; exam2[][]=exam[100][3]; exam3[][]=exam[100][3]; for(i=0;i<100;i++); { if(exam1[i] <=90 && exam1[i] >=100) { above90++; cout << above90; } } return exam1[i],exam2[i],exam3[i]; } int read_file_in_array(int exam[100][3]) { ifstream infile; int num, i=0,j=0; infile.open("grades.txt");// file containing numbers in 3 columns if(infile.fail()) // checks to see if file opended { cout << "error" << endl; } while(!infile.eof()) // reads file to end of line { for(i=0;i<100;i++); // array numbers less than 100 { for(j=0;j<3;j++); // while reading get 1st array or element infile >> exam[i][j]; cout << exam[i][j] << endl; } } infile.close(); return exam[i][j]; }

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  • Do While loop breaks after incorrect input?

    - by Daminkz
    I am trying to have a loop continue to prompt the user for an option. When I get a string of characters instead of an int, the program loops indefinitely. I have tried setting the variable result to NULL, clearing the input stream, and have enclosed in try{}catch blocks (not in this example). Can anyone explain to me why this is? #include <iostream> #include <vector> #include <string> using namespace std; int menu(string question, vector<string> options) { int result; cout << question << endl; for(int i = 0; i < options.size(); i++) { cout << '[' << i << ']' << options[i] << endl; } bool ans = false; do { cin >> result; cin.ignore(1000, 10); if (result < options.size() ) { ans = true; } else { cout << "You must enter a valid option." << endl; result = NULL; ans = false; } } while(!ans); return result; } int main() { string menuQuestion = "Welcome to my game. What would you like to do?"; vector<string> mainMenu; mainMenu.push_back("Play Game"); mainMenu.push_back("Load Game"); mainMenu.push_back("About"); mainMenu.push_back("Exit"); int result = menu(menuQuestion, mainMenu); cout << "You entered: " << result << endl; return 0; }

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  • c++ template function compiles in header but not implementation

    - by flies
    I'm trying to learn templates and I've run into this confounding error. I'm declaring some functions in a header file and I want to make a separate implementation file where the functions will be defined. Here's the code that calls the header (dum.cpp): #include <iostream> #include <vector> #include <string> #include "dumper2.h" int main() { std::vector<int> v; for (int i=0; i<10; i++) { v.push_back(i); } test(); std::string s = ", "; dumpVector(v,s); } now, here's a working header file (dumper2.h): #include <iostream> #include <string> #include <vector> void test(); template <class T> void dumpVector( std::vector<T> v,std::string sep); template <class T> void dumpVector(std::vector<T> v, std::string sep) { typename std::vector<T>::iterator vi; vi = v.begin(); std::cout << *vi; vi++; for (;vi<v.end();vi++) { std::cout << sep << *vi ; } std::cout << "\n"; return; } with implentation (dumper2.cpp): #include <iostream> #include "dumper2.h" void test() { std::cout << "!olleh dlrow\n"; } the weird thing is that if I move the code that defines dumpVector from the .h to the .cpp file, I get the following error: g++ -c dumper2.cpp -Wall -Wno-deprecated g++ dum.cpp -o dum dumper2.o -Wall -Wno-deprecated /tmp/ccKD2e3G.o: In function `main': dum.cpp:(.text+0xce): undefined reference to `void dumpVector<int>(std::vector<int, std::allocator<int> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >)' collect2: ld returned 1 exit status make: *** [dum] Error 1 So why does it work one way and not the other? Clearly the compiler can find test(), so why can't it find dumpVector?

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  • Comparing char for validation in C++

    - by Corey Starbird
    /* PROGRAM: Ch6_14.cpp Written by Corey Starbird This program calculates the balance owed to a hospital for a patient. Last modified: 10/28/13 */ #include <iostream> #include <fstream> #include <iomanip> #include <string> using namespace std; // Prototypes for In-patient and Out-patient functions. double stayTotal (int, double, double, double); // For In-patients double stayTotal (double, double); // For Out-patients int main() { char patientType; // In-patient (I or i) or Out-patient (O or o) double rate, // Daily rate for the In-patient stay servCharge, // Service charge for the stay medCharge, // Medication charge for the stay inTotal, // Total for the In-patient stay outTotal; // Total for the Out-patient stay int days; // Number of days for the In-patient stay // Find out if they were an In-patient or an Out-patient cout << "Welcome, please enter (I) for an In-patient or (O) for an Out-patient:" << endl; cin >> patientType; while (patientType != 'I' || 'i' || 'O' || 'o') { cout << "Invalid entry. Please enter either (I) for an In-patient or (O) for an Out-patient:" << endl; cin >> patientType; } cout << "FIN"; return 0; } Hey, brand new to C++ here. I am working on a project and I'm having trouble figuring out why my validation for patientTypeisn't working properly. I first had double quotes, but realized that would denote strings. I changed them to single quotes, my program will compile and run now, but the while loop runs no matter what I enter, I, i, O, o, or anything else. I don't know why the while loop isn't checking the condition, seeing that I did enter one of the characters in the condition, and move on to cout. Probably a simple mistake, but I thank you in advance.

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  • curl problems in c++ class

    - by Danilo
    I read a few articles on c++ / curl here on stackoverflow and assembled the following. The main goal is to handle the whole request in an instance of a class -- and maybe later in a secondary thread. My problem is: "content_" seems to stay empty though its the same addr and HttpFetch.h: class HttpFetch { private: CURL *curl; static size_t handle(char * data, size_t size, size_t nmemb, void * p); size_t handle_impl(char * data, size_t size, size_t nmemb); public: std::string content_; static std::string url_; HttpFetch(std::string url); void start(); std::string data(); }; HttpFetch.cpp: HttpFetch::HttpFetch(std::string url) { curl_global_init(CURL_GLOBAL_ALL); //pretty obvious curl = curl_easy_init(); content_.append("Test"); std::cout << &content_ << "\n"; curl_easy_setopt(curl, CURLOPT_URL, &url); curl_easy_setopt(curl, CURLOPT_WRITEDATA, &content_); curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &HttpFetch::handle); //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); //tell curl to output its progress curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); //std::cout << &content_ << "\n"; } void HttpFetch::start() { curl_easy_perform(curl); curl_easy_cleanup(curl); } size_t HttpFetch::handle(char * data, size_t size, size_t nmemb, void * p) { std::string *stuff = reinterpret_cast<std::string*>(p); stuff->append(data, size * nmemb); std::cout << stuff << "\n"; // has content from data in it! return size * nmemb; } main.cpp: #include "HttpFetch.h" int main(int argc, const char * argv[]) { HttpFetch call = *new HttpFetch("http://www.example.com"); call.start(); ::std::cout << call.content_ << "\n" } Thanks in advance

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  • Program crash on deque from queue

    - by SwedishGit
    My first question asked here, so please excuse if I fail to include something... I'm working on a homework project, which basically consists of creating a "Jukebox" (importing/exporting albums from txt files, creating and "playing" a playlist, etc.). I've become stuck on one point: When "playing" the playlist, which consists of a self-made Queue, a copy of it is made from which songs are dequeued and printed out with a time delay. This appears to run fine on the first run through the program, but if the "play" option is chosen again (with the same playlist, created from a different menu option), it crashes before managing to print the first song. It also crashes if creating a new playlist, but then it manages to print some songs (seem to depend on the number of songs in the first/new playlists...) before crashing. With printouts I've been able to track the crashing down to being on the "item = n-data" call in the deque function... but can't get my head around why this would crash. Below is the code I think should be relevant... let me know if there are other parts that would help if I include. Edit: The Debug Error shown on crash is: R6010 abort() has been called The method to play from the playlist: void Jukebox::playList() { if(songList.getNodes() > 0) { Queue tmpList(songList); Song tmpSong; while(tmpList.deque(tmpSong)) { clock_t temp; temp = clock () + 2 * CLOCKS_PER_SEC ; while (clock() < temp) {} } } else cout << "There are no songs in the playlist!" << endl; } Queue: // Queue.h - Projekt-uppgift // Håkan Sjölin 2014-05-31 //----------------------------------------------------------------------------- #ifndef queue_h #define queue_h #include "Song.h" using namespace std; typedef Song Item; class Node; class Queue { private: Node *first; Node *last; int nodes; public: Queue():first(nullptr),last(nullptr),nodes(0){}; ~Queue(); void enque(Item item); bool deque(Item &item); int getNodes() const { return nodes; } void empty(); }; #endif // Queue.cpp - Projekt-uppgift // Håkan Sjölin 2014-05-31 //----------------------------------------------------------------------------- #include "queue.h" using namespace std; class Node { public: Node *next; Item data; Node (Node *n, Item newData) : next(n), data(newData) {} }; //------------------------------------------------------------------------------ // Funktionsdefinitioner för klassen Queue //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ // Destruktor //------------------------------------------------------------------------------ Queue::~Queue() { while(first!=0) { Node *tmp = first; first = first->next; delete tmp; } } //------------------------------------------------------------------------------ // Lägg till data sist i kön //------------------------------------------------------------------------------ void Queue::enque(Item item) { Node *pNew = new Node(0,item); if(getNodes() < 1) first = pNew; else last->next = pNew; last = pNew; nodes++; } //------------------------------------------------------------------------------ // Ta bort data först i kön //------------------------------------------------------------------------------ bool Queue::deque(Item &item) { if(getNodes() < 1) return false; //cout << "deque: test2" << endl; Node *n = first; //cout << "deque: test3" << endl; //cout << "item = " << item << endl; //cout << "first = " << first << endl; //cout << "n->data = " << n->data << endl; item = n->data; //cout << "deque: test4" << endl; first = first->next; //delete n; nodes--; if(getNodes() < 1) // Kön BLEV tom last = nullptr; return true; } //------------------------------------------------------------------------------ // Töm kön //------------------------------------------------------------------------------ void Queue::empty() { while (getNodes() > 0) { Item item; deque(item); } } //------------------------------------------------------------------------------ Song: // Song.h - Projekt-uppgift // Håkan Sjölin 2014-05-15 //----------------------------------------------------------------------------- #ifndef song_h #define song_h #include "Time.h" #include <string> #include <iostream> using namespace std; class Song { private: string title; string artist; Time length; public: Song(); Song(string pTitle, string pArtist, Time pLength); // Setfunktioner void setTitle(string pTitle); void setArtist(string pArtist); void setLength(Time pLength); // Getfunktioner string getTitle() const { return title;} string getArtist() const { return artist;} Time getLength() const { return length;} }; ostream &operator<<(ostream &os, const Song &song); istream &operator>>(istream &is, Song &song); #endif // Song.cpp - Projekt-uppgift // Håkan Sjölin 2014-05-15 //----------------------------------------------------------------------------- #include "Song.h" #include "Constants.h" #include <iostream> //------------------------------------------------------------------------------ // Definiering av Songs medlemsfunktioner //------------------------------------------------------------------------------ // Fövald konstruktor //------------------------------------------------------------------------------ Song::Song() { } //------------------------------------------------------------------------------ // Initieringskonstruktor //------------------------------------------------------------------------------ Song::Song(string pTitle, string pArtist, Time pLength) { title = pTitle; artist = pArtist; length = pLength; } //------------------------------------------------------------------------------ // Setfunktioner //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ // setTitle // Ange titel //------------------------------------------------------------------------------ void Song::setTitle(string pTitle) { title = pTitle; } //------------------------------------------------------------------------------ // setArtist // Ange artist //------------------------------------------------------------------------------ void Song::setArtist(string pArtist) { artist = pArtist; } //------------------------------------------------------------------------------ // setTitle // Ange titel //------------------------------------------------------------------------------ void Song::setLength(Time pLength) { length = pLength; } //--------------------------------------------------------------------------- // Överlagring av utskriftsoperatorn //--------------------------------------------------------------------------- ostream &operator<<(ostream &os, const Song &song) { os << song.getTitle() << DELIM << song.getArtist() << DELIM << song.getLength(); return os; } //--------------------------------------------------------------------------- // Överlagring av inmatningsoperatorn //--------------------------------------------------------------------------- istream &operator>>(istream &is, Song &song) { string tmpString; Time tmpLength; getline(is, tmpString, DELIM); song.setTitle(tmpString); getline(is, tmpString, DELIM); song.setArtist(tmpString); is >> tmpLength; is.get(); song.setLength(tmpLength); return is; } //--------------------------------------------------------------------------- Album: // Album.h - Projekt-uppgift // Håkan Sjölin 2014-05-17 //----------------------------------------------------------------------------- #ifndef album_h #define album_h #include "Song.h" #include <string> #include <vector> #include <iostream> using namespace std; class Album { private: string name; vector<Song> songs; public: Album(); Album(string pNameTitle, vector<Song> pSongs); // Setfunktioner void setName(string pName); // Getfunktioner string getName() const { return name;} vector<Song> getSongs() const { return songs;} int getNumberOfSongs() const { return songs.size();} Time getTotalTime() const; void addSong(Song pSong); bool operator<(const Album &album) const; }; ostream &operator<<(ostream &os, const Album &album); istream &operator>>(istream &is, Album &album); #endif // Album.cpp - Projekt-uppgift // Håkan Sjölin 2014-05-17 //----------------------------------------------------------------------------- #include "Album.h" #include "Constants.h" #include <iostream> #include <string> //------------------------------------------------------------------------------ // Definiering av Albums medlemsfunktioner //------------------------------------------------------------------------------ // Fövald konstruktor //------------------------------------------------------------------------------ Album::Album() { } //------------------------------------------------------------------------------ // Initieringskonstruktor //------------------------------------------------------------------------------ Album::Album(string pName, vector<Song> pSongs) { name = pName; songs = pSongs; } //------------------------------------------------------------------------------ // Setfunktioner //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ // setName // Ange namn //------------------------------------------------------------------------------ void Album::setName(string pName) { name = pName; } //------------------------------------------------------------------------------ // addSong // Lägg till song //------------------------------------------------------------------------------ void Album::addSong(Song pSong) { songs.push_back(pSong); } //------------------------------------------------------------------------------ // getTotalTime // Returnera total speltid //------------------------------------------------------------------------------ Time Album::getTotalTime() const { Time tTime(0,0,0); for(Song s : songs) { tTime = tTime + s.getLength(); } return tTime; } //--------------------------------------------------------------------------- // Mindre än //--------------------------------------------------------------------------- bool Album::operator<(const Album &album) const { return getTotalTime() < album.getTotalTime(); } //--------------------------------------------------------------------------- // Överlagring av utskriftsoperatorn //--------------------------------------------------------------------------- ostream &operator<<(ostream &os, const Album &album) { os << album.getName() << endl; os << album.getNumberOfSongs() << endl; for (size_t i = 0; i < album.getSongs().size(); i++) os << album.getSongs().at(i) << endl; return os; } //--------------------------------------------------------------------------- // Överlagring av inmatningsoperatorn //--------------------------------------------------------------------------- istream &operator>>(istream &is, Album &album) { string tmpString; int tmpNumberOfSongs; Song tmpSong; getline(is, tmpString); album.setName(tmpString); is >> tmpNumberOfSongs; is.get(); for (int i = 0; i < tmpNumberOfSongs; i++) { is >> tmpSong; album.addSong(tmpSong); } return is; } //--------------------------------------------------------------------------- Time: // Time.h - Projekt-uppgift // Håkan Sjölin 2014-05-15 //----------------------------------------------------------------------------- #ifndef time_h #define time_h #include <iostream> using namespace std; class Time { private: int hours; int minutes; int seconds; public: Time(); Time(int pHour, int pMinute, int pSecond); // Setfunktioner void setHour(int pHour); void setMinute(int pMinute); void setSecond(int pSecond); // Getfunktioner int getHour() const { return hours;} int getMinute() const { return minutes;} int getSecond() const { return seconds;} Time operator+(const Time &time) const; bool operator==(const Time &time) const; bool operator<(const Time &time) const; }; ostream &operator<<(ostream &os, const Time &time); istream &operator>>(istream &is, Time &Time); #endif // Time.cpp - Projekt-uppgift // Håkan Sjölin 2014-05-15 //----------------------------------------------------------------------------- #include "Time.h" #include <iostream> //------------------------------------------------------------------------------ // Definiering av Times medlemsfunktioner //------------------------------------------------------------------------------ // Fövald konstruktor //------------------------------------------------------------------------------ Time::Time() { } //------------------------------------------------------------------------------ // Initieringskonstruktor //------------------------------------------------------------------------------ Time::Time(int pHour, int pMinute, int pSecond) { setHour(pHour); setMinute(pMinute); setSecond(pSecond); } //------------------------------------------------------------------------------ // Setfunktioner //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ // setHour // Ange timme //------------------------------------------------------------------------------ void Time::setHour(int pHour) { if(pHour>-1) hours = pHour; else hours = 0; } //------------------------------------------------------------------------------ // setMinute // Ange minut //------------------------------------------------------------------------------ void Time::setMinute(int pMinute) { if(pMinute < 60 && pMinute > -1) { minutes = pMinute; } else minutes = 0; } //------------------------------------------------------------------------------ // setSecond // Ange sekund //------------------------------------------------------------------------------ void Time::setSecond(int pSecond) { if(pSecond < 60 && pSecond > -1) { seconds = pSecond; } else seconds = 0; } //--------------------------------------------------------------------------- // Överlagring av utskriftsoperatorn //--------------------------------------------------------------------------- ostream &operator<<(ostream &os, const Time &time) { os << time.getHour()*3600+time.getMinute()*60+time.getSecond(); return os; } //--------------------------------------------------------------------------- // Överlagring av inmatningsoperatorn //--------------------------------------------------------------------------- istream &operator>>(istream &is, Time &time) { int tmp; is >> tmp; time.setSecond(tmp%60); time.setMinute((tmp/60)%60); time.setHour(tmp/3600); return is; } //--------------------------------------------------------------------------- // Likhet //-------------------------------------------------------------------------- bool Time::operator==(const Time &time) const { return hours == time.getHour() && minutes == time.getMinute() && seconds == time.getSecond(); } //--------------------------------------------------------------------------- // Mindre än //--------------------------------------------------------------------------- bool Time::operator<(const Time &time) const { if(hours == time.getHour()) { if(minutes == time.getMinute()) { return seconds < time.getSecond(); } else { return minutes < time.getMinute(); } } else { return hours < time.getHour(); } } //--------------------------------------------------------------------------- // Addition //--------------------------------------------------------------------------- Time Time::operator+(const Time &time) const { return Time(hours+time.getHour() + (minutes+time.getMinute() + (seconds+time.getSecond())/60)/60, (minutes+time.getMinute() + (seconds+time.getSecond())/60)%60, (seconds+time.getSecond())%60); } //--------------------------------------------------------------------------- Thanks in advance for any help! Edit2: Didn't think of including the more detailed crash info (as it didn't show in the crash pop-up, so to say). Anyway, here it is: Output: 'Jukebox.exe' (Win32): Loaded 'C:\Users\Håkan\Documents\Studier - IT\Objektbaserad programmering i C++\Inlämningsuppgifter\Projekt\Jukebox\Debug\Jukebox.exe'. Symbols loaded. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ntdll.dll'. Cannot find or open the PDB file. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\kernel32.dll'. Cannot find or open the PDB file. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\KernelBase.dll'. Cannot find or open the PDB file. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcp110d.dll'. Symbols loaded. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcr110d.dll'. Symbols loaded. The thread 0xe50 has exited with code 0 (0x0). Unhandled exception at 0x0083630C in Jukebox.exe: 0xC0000005: Access violation reading location 0x0000003C. Call stack: > Jukebox.exe!Song::getLength() Line 27 C++ Jukebox.exe!operator<<(std::basic_ostream<char,std::char_traits<char> > & os, const Song & song) Line 59 C++ Jukebox.exe!Queue::deque(Song & item) Line 55 C++ Jukebox.exe!Jukebox::playList() Line 493 C++ Jukebox.exe!Jukebox::play() Line 385 C++ Jukebox.exe!Jukebox::run() Line 536 C++ Jukebox.exe!main() Line 547 C++ Jukebox.exe!__tmainCRTStartup() Line 536 C Jukebox.exe!mainCRTStartup() Line 377 C kernel32.dll!754d86e3() Unknown [Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll] ntdll.dll!7748bf39() Unknown ntdll.dll!7748bf0c() Unknown

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  • What's wrong with my destructor?

    - by Ahmed Sharara
    // Sparse Array Assignment.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include<iostream> using namespace std; struct node{ int row; int col; int value; node* next_in_row; node* next_in_col; }; class MultiLinkedListSparseArray { private: char *logfile; node** rowPtr; node** colPtr; // used in constructor node* find_node(node* out); node* ins_node(node* ins,int col); node* in_node(node* ins,node* z); node* get(node* in,int row,int col); bool exist(node* so,int row,int col); node* dummy; int rowd,cold; //add anything you need public: MultiLinkedListSparseArray(int rows, int cols); ~MultiLinkedListSparseArray(); void setCell(int row, int col, int value); int getCell(int row, int col); void display(); void log(char *s); void dump(); }; MultiLinkedListSparseArray::MultiLinkedListSparseArray(int rows,int cols){ rowPtr=new node* [rows+1]; colPtr=new node* [cols+1]; for(int n=0;n<=rows;n++) rowPtr[n]=NULL; for(int i=0;i<=cols;i++) colPtr[i]=NULL; rowd=rows;cold=cols; } MultiLinkedListSparseArray::~MultiLinkedListSparseArray(){ cout<<"array is deleted"<<endl; for(int i=rowd;i>=0;i--){ for(int j=cold;j>=0;j--){ if(exist(rowPtr[i],i,j)) delete get(rowPtr[i],i,j); } } // it stops in the last loop & doesnt show the done word cout<<"done"<<endl; delete [] rowPtr; delete [] colPtr; delete dummy; } void MultiLinkedListSparseArray::log(char *s){ logfile=s; } void MultiLinkedListSparseArray::setCell(int row,int col,int value){ if(exist(rowPtr[row],row,col)){ (*get(rowPtr[row],row,col)).value=value; } else{ if(rowPtr[row]==NULL){ rowPtr[row]=new node; (*rowPtr[row]).value=value; (*rowPtr[row]).row=row; (*rowPtr[row]).col=col; (*rowPtr[row]).next_in_row=NULL; (*rowPtr[row]).next_in_col=NULL; } else if((*find_node(rowPtr[row])).col<col){ node* out; out=find_node(rowPtr[row]); (*out).next_in_row=new node; (*((*out).next_in_row)).col=col; (*((*out).next_in_row)).row=row; (*((*out).next_in_row)).value=value; (*((*out).next_in_row)).next_in_row=NULL; } else if((*find_node(rowPtr[row])).col>col){ node* ins; ins=in_node(rowPtr[row],ins_node(rowPtr[row],col)); node* g=(*ins).next_in_row; (*ins).next_in_row=new node; (*((*ins).next_in_row)).col=col; (*(*ins).next_in_row).row=row; (*(*ins).next_in_row).value=value; (*(*ins).next_in_row).next_in_row=g; } } } int MultiLinkedListSparseArray::getCell(int row,int col){ return (*get(rowPtr[row],row,col)).value; } void MultiLinkedListSparseArray::display(){ for(int i=1;i<=5;i++){ for(int j=1;j<=5;j++){ if(exist(rowPtr[i],i,j)) cout<<(*get(rowPtr[i],i,j)).value<<" "; else cout<<"0"<<" "; } cout<<endl; } } node* MultiLinkedListSparseArray::find_node(node* out) { while((*out).next_in_row!=NULL) out=(*out).next_in_row; return out; } node* MultiLinkedListSparseArray::ins_node(node* ins,int col){ while(!((*ins).col>col)) ins=(*ins).next_in_row; return ins; } node* MultiLinkedListSparseArray::in_node(node* ins,node* z){ while((*ins).next_in_row!=z) ins=(*ins).next_in_col; return ins; } node* MultiLinkedListSparseArray::get(node* in,int row,int col){ dummy=new node; dummy->value=0; while((*in).col!=col){ if((*in).next_in_row==NULL){ return dummy; } in=(*in).next_in_row; } return in; } bool MultiLinkedListSparseArray::exist(node* so,int row,int col){ if(so==NULL) return false; else{ while((*so).col!=col){ if((*so).next_in_row==NULL) return false; else so=(*so).next_in_row; } return true; } }

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